Non-Newtonian Fluids

Last week the kids and I watched a video about college kids ‘walking on water’ – the boys were fascinated and asked if we could do it too, lol! My answer to that was “not today, it’s too cold out and I don’t have enough ingredients”, lol! But I did have enough to make a small batch each of OOBLECK!

Because EVERYTHING has to have a learning element to it, I decided to read ‘Bartholomew and the Oobleck’ by Dr Seuss and then we watched another couple of fun videos.

The Sciency Stuff

We learned that Oobleck is a non-Newtonian fluid – meaning that it ignores Newton’s Law of Viscosity (flow). All fluids have a property known as viscosity which is the measurable “gooeyness” of the fluid or its resistance to flowing.

Newton stated that the viscosity of a fluid can be changed only by altering the fluid’s temperature. A non-Newtonian fluid doesn’t have the same dependence on temperature because its viscosity changes when stress or a force, not heat, is applied. When you squeeze a handful of the goop you made, the particles of cornstarch come closer together and trap the water between them. Its viscosity increases and it acts like a solid – for a split second. When you release the pressure, water fills the spaces between cornstarch particles again and the goop behaves like a liquid.

The Messy Stuff

Once we had talked about all the serious stuff we decided to get all ‘pre-school’ and get our hands messy! We added food colouring to our goop to make interesting patterns. The colour did not mix in like it would normally, the marbling was stunning.

Anyway, here’s the simple recipe for those that are interested…

  • 1 part water
  • 1.5 – 2 parts cornflour
  • Food Colouring
  • Start with the water in a mixing bowl and then add the cornflour a little at a time until it has a gooey consistency. It can be really difficult to mix with a spoon so just use your hands. Then add a few drops of colour and watched it swirl around.

The Pictures

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